A prime number is a counting number greater than 1 whose only factors are 1 and itself. A composite number is a counting number that is not prime. To determine if a number is prime, divide it by each ...A prime number is a counting number greater than 1 whose only factors are 1 and itself. A composite number is a counting number that is not prime. To determine if a number is prime, divide it by each of the primes, in order, to see if it is a factor of the number. Start with 2 and stop when the quotient is smaller than the divisor or when a prime factor is found. If the number has a prime factor, then it is a composite number. If it has no prime factors, then the number is prime.
